Mapping of mutations associated with neurovirulence in monkeys infected with Sabin 1 poliovirus revertants selected at high temperature

Abstract

Poliovirus type 1 neurovirulence is difficult to analyze because of the 56 mutations which differentiate the neurovirulent Mahoney strain from the attenuated Sabin strain. We have isolated four neurovirulent mutants which differ from the temperature-sensitive parental Sabin 1 strain by only a few mutations, using selection for temperature resistance: mutant S137C, was isolated at 37.5°C, S138C5 was isolated at 38.5°C, and S139C6 and S139C10 were isolated at 39.5°C. All four mutants had a positive reproductive capacity at supraoptimal temperature (Rct+ phenotype). Mutant S137C1 induced paralysis in two of four cynomolgus monkeys, and the three other mutants induced paralysis in four of four monkeys. The lesion score increased from the S137C, mutant to the S139 mutants. To map the mutations associated with thermoresistance and neurovirulence, we sequenced all regions in which the Sabin 1 genome differs from the Mahoney genome. The S137C, mutant had one mutation in the 5' noncoding region and another in the 3' noncoding region. Mutant S138C. had these mutations plus another mutation in the 3D polymerase gene. The S139 mutants had three additional mutations in the capsid protein region. The mutations were located at positions at which the Sabin 1 and Mahoney genomes differ, except for the mutation in the 5' noncoding region. The noncoding-region mutations apparently confer a low degree of neurovirulence. The 3D polymerase mutation, which distinguishes S138C. and S139 mutants from S137C1, is probably responsible for the high neurovirulence of S138C5 and S139 mutants. The capsid region mutations may contribute to the neurovirulence of the S139 mutants, which was the highest among the mutants.

Oral Poliovirus Vaccine Evolution and Insights Relevant to Modeling the Risks of Circulating Vaccine‐Derived Polioviruses (cVDPVs)

“…(113) Cell culture experiments showed that OPV1 viruses lose a few attenuating mutations after exposure to high temperature yielding viruses with comparable neurovirulence to Mahoney virus based on testing in monkeys. (85) A few limited studies show the reversion of OPV1 following transmission in multiple people. One study monitored the change of neurovirulence of virus through five successive passages at approximately one-week intervals in healthy infants aged 8-12 months fed mOPV1.…”

“…Numerous studies show potential attenuating mutations for each serotype of OPV virus based on: (1) sequence comparisons between OPV virus strains and parental WPVs, (75,76) (2) sequence comparisons and/or neurovirulence testing in monkeys or mice of recombinant virus strains (i.e., swapping genetic segments between attenuated and neurovirulent strains) and/or site-directed mutants, (47,50,(77)(78)(79)(80)(81)(82)(83)(84) (3) OPV-related virus mutant strains after exposure to high temperature, (85) (4) OPV-related virus strains excreted by immunocompetent vaccine recipients without VAPP, (48,(86)(87)(88)(89) (5) OPV-related virus strains isolated from VAPP cases, (44)(45)(46)48,(90)(91)(92)(93)(94)(95)(96)(97)(98)(99) (6) strains isolated during cVDPV outbreaks, (15,57,100,101) (7) strains excreted by immunodeficient VDPV excretors, (102-106) (8) strains obtained during sequential passages after OPV administration in humans, (107) (9) strains obtained during sequential passages of OPV-related viruses in monkey tissues, (108) and (10) strains obtained from passages in cell culture. …”

Emergency Services of Viral RNAs: Repair and Remodeling

“…As noted above, the Sabin strain of this serotype has a destabilizing mutation at position 480 (A to G) contributing to its attenuated phenotype, but this destabilization is not usually conserved in vaccinees and their contacts. The strengthening of this base pairing might be accomplished not only by the reversion (G 480 A) but also by a compensating pseudoreversion (U 525 C) (311,322), which also resulted in a similar increase in virulence (323) and in restoration of the in vitro translation efficiency (311). Structural modeling suggested that G 481 of the predecessor of the Sabin-2 strain, strain P712, could potentially participate in a long-range interaction with C 398 , supporting the generation of a tertiary structure element (311) (Fig.…”

Consistent selection of mutations in the 5′‐untranslated region of oral poliovirus vaccine upon passaging in vitro

“…Sabin type 1 and type 2 have different mutations in the same RNA domain: A to G transition a t position 480 in type 1, and G to A transition at position 481 in type 2. Both of these mutations are related to viral attenuation [Christodoulou et al, 1990;Kawamura et al, 1989;Macadam et al, 1991a,b;Moss et al, 1989;Ren et al, 19911 and are often found in virus isolates from vaccinees [Minor and Dunn, 1988;Muzychenko et al, 19911. We performed MAPREC analysis of type 1 and type 2 OPV passaged in Vero cells and found that mutations at these positions also rapidly accumulated in cell culture (Fig.…”

“…Studies on the accumulation of revertants during cultivation of the Sabin strains in different cell substrates at various levels of confluence showed that the rate of revertant selection varied significantly and seemed t o be dependent on cellular factors. Mutations a t other sites of the same F-domain of the 5'-untranslated region were implicated in attenuation of OPV of types 1 and 2 [Christodoulou et al, 1990;Kawamura et al, 1989;Macadam et al, 1991a,b;Moss et al, 1989;Ren et al, 19911. In this communication we demonstrate that G +A reversion at position 480 of Sabin type 1, and A + G reversion at position 481 of Sabin type 2, also accumulate during virus passaging in vitro and therefore reversion in the F-domain of the poliovirus 5'-untranslated region is a common phenomenon for all three Sabin serotypes. The results obtained in this netic stability described in this paper may be useful for the improvement of vaccine manufacturing consistency and evaluation of the stability of prospective vaccine strains.…”